[ubuntu_studio] Jack won't start

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http://ubuntuforums.org – I'm running Ubuntu Studio 12.04 on my desktop computer. All of a sudden, jack has stopped working. Under the settings window, it no longer shows my usb devices, a Focusrite Scarlett 2i2 or an Art Dual Preamp, at least not by name. They both work fine until I try to start jack. Everything works fine from the live CD. Under the installed system, jack won't start. I get a series of 4 popups. The only thing I've done recently other than normal updates that might have caused this is I installed the MATE shell/Desktop. I uninstalled it, but nothing changed. I'm stumped. I really hate to thi (Hardware)